It has previously been proposed--see the referenced Swiss Pat. No. 638,436 or U.S. equivalent 4,248,415--to supply single sheets or copy material from a stack to a platen of a writing or printing type office machine, such as a typewriter, an output printer, a word processor printer or the like. A separating roller engages the topmost sheet or copy material from a stack and supplies it to an input slit between the platen and a counter roller, or counter surface. The separating rollers frictionally engage the top sheet and are coupled over a free wheeling, or overrunning clutch arrangement to gearing, so that, when the gearing is driven, the sheet is fed; when the sheet is grasped by the driven platen, the separating rollers can run freely, not requiring any further drive, or, if the drive for the separating roller continues to operate, the separating rollers can overrun the drive speed of the drive to the separating rollers; that is, they can freely operate at the higher speed. The gearing, or drive arrangement for the separating roller can receive drive powered directly from the platen of the typewriter, printer or the like which, for simplicity, may be referred to hereinafter as a "printer".
One known arrangement utilizes a printer platen which, in order to feed a sheet, first rotates in a direction counter to the sheet feeding direction. Such counter rotation, which may also be used for alignment of a sheet, will be referred to as the "reverse" or "sheet aligning direction" of rotation of the roller. To feed a sheet, the platen, then, rotates first in the sheet aligning or reverse direction over a predetermined angle of rotation; thereafter, it rotates forwardly, or in the sheet feeding direction, for a certain angular distance, which may be small. Thereafter, the platen again reverses, and operates in reverse, or sheet aligning direction, for a predetermined distance, and until the sheet reaches the gap between the platen and a first pressure roller, so that the sheet can then be grasped. The platen then again reverses and pulls the sheet into the printer by rotation of the platen in the sheet feeding, or forward direction.
The sequential operation, first forwardly--for example to eject a previously printed sheet--then reversely by a predetermined angle, then forwardly by a second predetermined angle, then again reversely, and then again forwardly, requires a relatively expensive and complex ratchet and direction sensing apparatus as well as programming of an office machine, such as a word processor, computer output printer or automatic or semi-automatic typewriter.